FreeBSD/Linux Kernel Cross Reference
sys/dev/iicbus/mux/iicmux.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause
      *
      * Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #ifndef __IICMUX_H
    #define __IICMUX_H
    
    #define IICMUX_MAX_BUSES        16      /* More than any available mux chip. */
    
    /*
     * IICMUX_SELECT_IDLE instructs the mux hardware driver to do whatever it is
     * configured to do when the downstream buses are idle.  Hardware has varying
     * capabilities; it may disconnect all downstream buses, or connect a specific
     * bus, or just leave whatever bus was last used connected.  Hardware which is
     * capable of various choices will have some mechanism to configure the choice
     * which is handled outside of the iicmux framework.
     */
    #define IICMUX_SELECT_IDLE      (-1)
    
    /*
     * The iicmux softc; chip drivers should embed one of these as the first member
     * variable of their own softc struct, and must call iicmux_attach() to
     * initialize it before calling any other iicmux functions.
     */
    struct iicmux_softc {
            device_t        busdev;   /* Upstream i2c bus (may not be our parent). */
            device_t        dev;      /* Ourself. */
            int             maxbus;   /* Index of highest populated busdevs slot. */
            int             numbuses; /* Number of buses supported by the chip. */
            int             debugmux; /* Write debug messages when > 0. */
            device_t        childdevs[IICMUX_MAX_BUSES]; /* Child bus instances. */
    #ifdef FDT
            phandle_t       childnodes[IICMUX_MAX_BUSES]; /* Child bus fdt nodes. */
    #endif
    };
    
    DECLARE_CLASS(iicmux_driver);
    
    /*
     * Helpers to call from attach/detach functions of chip-specific drivers.
     *
     * The iicmux_attach() function initializes the core driver's portion of the
     * softc, and creates child iicbus instances for any children it can identify
     * using hints and FDT data.  If a chip driver does its own device_add_child()
     * calls to add other downstream buses that participate in the mux switching, it
     * must call iicmux_add_child() to inform the core driver of the downstream
     * busidx<->device_t relationship.
     */
    int  iicmux_add_child(device_t dev, device_t child, int busidx);
    int  iicmux_attach(device_t dev, device_t busdev, int numbuses);
    int  iicmux_detach(device_t dev);
    
    #endif

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